Some types of mechanical power transmission devices include synchronizers to couple one rotatable component to another. For example, an automotive dual-clutch transmission typically includes two input shafts that receive power input from an engine flywheel via two input clutches, which selectively couple the flywheel to one or the other of the two input shafts. The two input shafts are coupled to a counter shaft via various pairs of meshed gears carried by the shafts.
At any given moment, the dual-clutch transmission conveys power in a synchronous fashion, wherein only one of the two input clutches is fully applied to couple the engine flywheel to only one of the two input shafts. Accordingly, power flows from the flywheel through only one fully applied clutch and its corresponding input shaft, and through only one of the pairs of meshed gears. The one input shaft is selected by applying its respective input clutch, and the one pair of meshed gears is selected with a synchronizer to couple one or the other of the pair of meshed gears to its respective shaft.